Timeline By QuonsetHut Sep 1, 1939 Germany Invades Poland Sep 3, 1939 Britain, France, Australia and New Zealand declare war on Germany Sep 10, 1939 Canada declares war on Germany Sep 17, 1939 Soviet Union invades eastern Poland Sep 17, 1939 Soviet Union invades eastern Poland. Sep 27, 1939 Surrender of Warsaw Feb 12, 1940 Finland signs peace treaty with Soviet Union Dec 7, 1943 US declares war on Japan